1. Field of the Invention
The present invention relates to a successive approximation register analog-to-digital converter (SAR ADC), and more particularly, to a SAR ADC and associated control method that can perform background calibration.
2. Description of the Prior Art
In a SAR ADC, a capacitance of each bit capacitor of a bit capacitor array may be different from its designed value due to semiconductor process variation, environment temperature variation or asymmetry/mismatch issue, therefore, errors may occur in digital outputs, and the linearity of the SAR ADC is worsened. To solve this problem, the bit capacitors needs to be calibrated, however, the conventional calibration methods generally have some problems such as influencing a working speed of the SAR ADC or limiting a swing of an input signal to avoid exceeding an encoding range of the SAR ADC . . . etc., causing inconvenience and trouble to a designer and operation errors.